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Etch Primer or Greyl Primer?


Mr Camouflage

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Here's one for all the sparypainters out there.

I'm stripping my 240 back to bare metal.

Should I prime it with etch primer (you know the brown/red primer, that seems to be what it was painted with origionally), or should I use the normal grey primer?

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You can get Etching primer in either the Red/Brown; Light Grey; or Dark Grey (almost black) colors.

Which color depends on what color you will be spraying on top of it.

Generally speaking, and going from memory:

Red/Brown: Dark Colors, Opaque paints, Most Dark Metallics.

Light Grey: Light Colors; Thinner paints; Light tone Metallics (must)

Dark Grey: Extreme Dark; or colors where the dark base will actually emphasize the base coat.

I won't get on my soapbox regarding stripping to bare metal. You've been around long enough to have read it once or twice, so suffice it to say that rarely is it recommended.

I think your biggest question should be whether to use High Fill Primer or Etch Prime followed by an Epoxy Filler.

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I do not use etch. I find that etch primer has many restrictions on its usage that makes it more of a pain. All etches are not the same. Some allow usuage over filler, others under, some neither, etc. I suggest you use epoxy primer. If you are stripping to bare metal, use a phosphoric acid to etch the metal before epoxy. This way you will have the advantages of epoxy and still have the metal etched. I use this technique all the time. You will find that epoxy is a very universal primer, thin it for sealer etc. If you ahve a lot od body work, you may want to cover the epoxy with a high build 2K. Body fillers can also be put over epoxy, which is another advantage. That way the epoxy protects the metal, and the filler is over top. I do all my work in epoxy, but no doubt most find 2K easy to fill small imperfections. Just make sure you have a fresh air system for the 2K since it is urethane based and contains isos. That is another advantage for epoxy, no isos.

Pete's Ponies Mustang RUSToration & Performance

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You're absolutely right Pete. I'd completely ignored Epoxy Primer in my post.

What I like about it is that (at least with some of them), you can top coat within 48 hours without having to scuff or wet-sand. Sometimes that can save a chunk of time.

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Originally posted by EScanlon

I won't get on my soapbox regarding stripping to bare metal......so suffice it to say that rarely is it recommended.

I Think on any car over 20 years old it is essential. especially if its been repainted , or had some smash repairs.

I have stripped original paint off pannels that looked fine to find rust under the primer. Sure its only little specks, but leave it a while and it will eat a hole throught the pannel.

Anyway my car had been repainted and i want to strip it to remove all the filler thats under the paint, and remove all the rust that's hiding under the 5 year old paint job the previous owner did.

So whats involved in etching with Phosphoric acid?

and what is the advantage in etching the metal?

What about epoxy etch primer?

Are there restrictions as to the type of top coat you use over epoxy primer?

The last car I painted, I just stripped, primed, hight filled and sanded then painted in Acrylic. But i had some kind of reaction with some anti rust killer stuff that i think was phosper based. So i had to use a barrier coat over the treated areas.

I wanna do it Right as I plan on owning this 240z for a very long time.

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one of the big pluses for epoxy is that there are no restrictions as far as what is put on top of it :o) I have seen but one mention of an etch epocy, and I do not believe the advertising. Basically etch is an acid, added to the primer. Epoxy, obviously as well known for adhesive, had tremendous adhesion proerties. It reqally needs nothing done to the metal. However, I use phosphoric acid to get rid of small surface rust, even so small you cannot see it. It etches the metal also for better adhesion; tooth. I use duPont 5717s. I dilute 2:1 as per instructions. From there, do as I say. Wipe the acid on with a scotch pad, working it in and removing rust. Then before it is dry, wipe it completely dry with paper towels. If you let any dry, then rewet with acid. It will leave a hazy look to the metal. Then I epoxy right over that. Everyones epoxy seems to react a little differently as far as sandability and such. I use Kirker epoxy and I find it is ver sandable after a couple days in the sun or cured with a heat light. Many put a 2K over the epoxy, so the epoxy is just your first layer. The 2K will alllow a lot of imperfections to be removed. I spray about 5 coats of epoxy, and block it. I have my body work done well though, a needed thing is using the epoxy to block. If using as a base only, spray two coats of epoxy, and then follow with several ocats of 2K urethane primer.

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